Insight into the photocatalytic mineralization of short chain chlorinated paraffins boosted by polydopamine and Ag nanoparticles.

Short chain chlorinated paraffins (SCCPs) have attracted increasing attention recently due to their widespread occurrence and persistence in the environment, long-distance transport, and bioaccumulation and toxicity. For the sake of photocatalytic elimination of SCCPs, a kind of polydopamine (PDA) based photocatalyst, echinus-like FeO@PDA-Ag hybrids have been synthesized via coating FeO with PDA by self-polymerization of dopamine and further loading silver nanoparticles by in situ reduction onto the surface of PDA shell. The photogenerated charges of FeO@PDA-Ag hybrids exhibit long lifetime from transient photovoltage signal, which is of benefit to participate in various subsequent reaction processes before their recombination. Benefiting from the coating of PDA shell and the deposition of Ag nanoparticles, FeO@PDA-Ag hybrids exhibit enhanced photocatalytic activity for the removel of SCCPs as investigated by the in situ Fourier transform infrared spectroscopy, 2.9 times as high as that of FeO, due to the reactive OH radicals. The density functional theory simulation demonstrates the key mechanism of the formation of conjugate bond in the dechlorination process as well as the final product of HCl. The simulation indicates that there are no regularities for the H-abstraction but the dechlorination usually occurs in the adjacent Cl atoms next to the C with H-abstraction.